Height 100vh for iOS

CSS

.my-element {
  height: 100vh; /* Fallback for browsers that do not support Custom Properties */
  height: calc(var(--vh, 1vh) * 100);
}

JS

// First we get the viewport height and we multiple it by 1% to get a value for a vh unit
let vh = window.innerHeight * 0.01;
// Then we set the value in the --vh custom property to the root of the document
document.documentElement.style.setProperty('--vh', `${vh}px`);

JS Eventlistener for rezising

// We listen to the resize event
window.addEventListener('resize', () => {
  // We execute the same script as before
  let vh = window.innerHeight * 0.01;
  document.documentElement.style.setProperty('--vh', `${vh}px`);
});